High temperature drop-off of a substrate

Abstract

A substrate to be processed in a high temperature processing chamber is preheated to avoid the problems associated with thermal shock when the substrate is dropped onto a heated susceptor. Preheating is effected by holding the substrate over a susceptor maintained at or near the processing temperature until the temperature of the substrate approaches the processing temperature. Thus, wafer warping and breakage are greatly reduced, and wafer throughput is improved because of time saved in maintaining the susceptor at constant temperature without cool down and reheat periods.

Description

REFERENCE TO RELATED APPLICATION[0001]This application is a continuation of application Ser. No. 10 / 291,879, filed Nov. 8, 2002, now U.S. Pat. No. 6,823,548, which is a divisional of application Ser. No. 09 / 840,532, filed Apr. 23, 2001, now U.S. Pat. No. 6,521,503, issued Feb. 18, 2003.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to substrate transport into processing chambers such as semiconductor chemical vapor deposition reactors, and, more particularly, to a method for increasing substrate throughput and reducing loss of product by reducing thermal shock to the substrate, which can cause breakage and poor quality of the deposited film.[0004]2. Description of the Related Art[0005]In the manufacture of integrated circuits, semiconductor substrates, or wafers, are often processed by chemical vapor deposition. Components of chemical vapor deposition systems include a reaction chamber that is configured to facilitate the controlled flo...

AI Technical Summary

Benefits of technology

[0011]If the wafer can be preheated to a temperature at or near the process temperature before being put on the susceptor, many benefits are accrued. Wafer throughput is increased because no additional time is needed to cool down and subsequently reheat the susceptor during wafer transfer. The temperature remains more uniform because the susceptor remains at or close to the process temperature instead of cycling through cooling and re-heating steps. There is reduced wafer breakage, resulting in less downtime. There is less wafer warping, resulting in better temperature consistency across the wafer and, therefore, better deposited film quality and uniformity. Consumable components, such as susceptors, undergo less thermal shock, thus prolonging their lifetimes and reducing the cost of operating the process equipment.

[0012]In general, an embodiment of the current invention comprises a substrate holder configured to support a single substrate for processing in a high temperature chamber. Processing methods that can use the apparatus and method recited herein include chemical vapor deposition, epitaxy, rapid thermal processing, etching, annealing, etc. A substrate handler can pick up an unprocessed substrate, put it on the substrate holder for processing and remove it after processing is complete. Heating is effected by a plurality of heating elements that are positioned to heat the substrate holder, and a control system maintains the substrate holder at a high temperature, such as more than 900° C., during wafer transfer. It is preferred that, while holding an unprocessed substrate, the substrate handler pause in a position close to and above the substrate holder for a period of time that allows the wafer to preheat. Preferably, the heating elements are radiant lamps that heat the wafer from above while the hot susceptor is heating the wafer from below, and thus minimize warpage of the wafer.

Problems solved by technology

The thermal effect experienced by the substrate usually varies throughout the extent of the substrate, that is to say that there are large thermal gradients, which may be difficult to mitigate.

This can lead to substrate warping and breakage and also to poor uniformity and quality of deposited films.

The susceptor also experiences thermal shock, which is repeated with wafer after wafer, and can ultimately reduce the working lifetime of the susceptor.

This repeated temperature cycling, solely for the purpose of wafer transfer, slows wafer throughput, so most manufacturers compromise by making only small temperature reductions during wafer transfer.

This results in less thermal shock but does not completely solve the problem.

While this pre-heating of the wafer reduced shock to the wafer, there was still some warpage of the wafer and the susceptor temperature was dropping during the delay.

Also, heat damage to the handler construction limited the temperature that could be maintained.

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